Yo Patty, Right on... and for those who want to see what can be done under literally all of the conditions Patty mentions, look at what the Israelis are doing. They're even selling their sweat pipe technology to the Jordanians, to keep the cost of war too high. (You don't want to drive a tank through your own orchards, even to attack your ancient enemy). Golan Heights, Smolan Heights, it's all about water.
I've often said that while Malthus postulated that food grew at an arithemetic rate, and populations grew at a geometric rate, he never knew that technology would grow at a trigonomic rate. But why spoil a perfectly good panic? Chicken Little was Right! (or CLWR!)